Method and apparatus to detect and monitor the frequency of obstructive sleep apnea

ABSTRACT

The present invention provides a method and apparatus for detecting and monitoring obstructive sleep apnea. The apparatus includes an intracardiac impedance sensor to measure intracardiac impedance, a movement sensor to measure an amount of movement of a patient, and a controller operatively coupled to said intracardiac impedance sensor and said movement sensor, said controller adapted to receive at least one of an intracardiac impedance and the amount of movement of the patient and detect obstructive sleep apnea based upon said intracardiac impedance and said movement.

BACKGROUND OF THE INVENTION

This application is divisional of application Ser. No. 11/284,283, filedon Nov. 21, 2005 which is a continuation of application Ser. No.10/136,778, filed Apr. 30, 2002.

FIELD OF THE INVENTION

This invention relates generally to implantable medical devices, andmore particularly, to a method and apparatus to automatically detect andmonitor the frequency of obstructive sleep apnea.

DESCRIPTION OF THE RELATED ART

Although the function of sleep is not well understood, one consequenceof an inadequate quantity or poor quality of sleep is an inability tomaintain adequate wakefulness. The amount of sleep an individual needsis thought to be neurologically determined and is generally stable overtime. Among other factors, an insufficient amount of sleep (i.e.,quantity of sleep) or a disruption of sleep continuity (i.e., quality ofsleep) will result in increased daytime sleepiness. Increased sleepinessin a person may cause a plethora of problems to that person as well asothers. Increased sleepiness is a major cause of accidents becausepeople who are sleepy are generally not fully aware of theirsurroundings. Additionally, because of this decreased awareness, aperson who does not receive the adequate quantity and quality of sleepat night may also be prone to decreased efficiency at home and at work.A sleepy person may also require frequent naps during the day torecuperate, thereby reducing productivity in the office as well as inthe chores of daily life. As a result, it is important for peoplegenerally to receive a good night's rest. However, many people havemedical conditions that prevent them from receiving a good night's rest.One such condition is sleep apnea.

Sleep apnea is generally defined as the cessation of breathing duringsleep. One type of a sleep apnea, obstructive sleep apnea (“OSA”), iscaused by repetitive upper airway obstruction during sleep as a resultof narrowing of the respiratory passages. Partial obstruction of thepassageways may simply lead to hypopnea. Prolonged obstruction of thepassageways, however, may lead to nocturnal arousals.

OSA is generally characterized by a sleep-related withdrawal of upperairway inspiratory muscle tone superimposed on a narrow, highlycompliant pharynx. As a result, the pharynx may during sleep, leading toobstructive apnea.

The cause of OSA is thought to be a combination of anatomiccharacteristics of the upper airway and abnormalities in theneuromuscular control of the muscles in the throat. Sleep apnea is morecommon in individuals with large tonsils, palate, and tongue, and with ashort thick neck. This anatomy may predispose the throat to easilycollapse. A badly deviated nasal septum or other nasal obstruction canalso worsen OSA because it limits the ability to breathe through thenose. Overweight individuals are also at high risk for OSA. Not allindividuals with these anatomic features will have OSA, and OSAoccasionally occurs in people with normal-appearing throats.

OSA may cause a variety of medical and other problems among patients.Cycles of sleep, snoring, obstruction, arousal, and sleep may occur manytimes throughout the night. Although such nocturnal arousals may lastonly a few seconds, they prevent a person from reaching the deep stagesof sleep, which the body generally needs to rest and replenish itsstrength. As a result, patients with OSA may not receive a restful sleepbecause of multiple nocturnal arousals.

Furthermore, multiple arousals with sleep fragmentation are likely tocause excessive daytime sleepiness and fatigue, cognitive impairment,depression, headaches, chest pain, and diminished sexual drive. OSA isgenerally associated with cardiovascular morbidity, including systemichypertension, pulmonary hypertension, ischemic heart disease, stroke,and cardiac arrhythmias. OSA is also usually associated with increasedmortality by negatively affecting the status, progression, and outcomesof previously existing conditions, such as congestive heart failure(“CHF”).

OSA is a disorder which is generally underdiagnosed and undertreated.Because OSA may worsen the effects of a previously existing condition,such as CHF, treatment of OSA may be beneficial to reduce its negativeon the previously existing condition. Once OSA has been properlydiagnosed, a variety of therapies may be available. Common OSA therapiesinclude non-surgical methods, such as continuous positive airwaypressure (“CPAP”), as well as surgical methods, such asuvulopalatopharyngoplasty (“UPPP”). Effective therapy for OSA can oftenreverse or ameliorate the problems associated with OSA.

One method of diagnosis for OSA is nocturnal polysomnography. Innocturnal polysomnography, multiple physiological parameters aremeasured while the patient sleeps in a laboratory. Typical parameters ina nocturnal polysomnography include eye movement observations (todetermine whether a patient has reached REM sleep), anelectroencephalogram (to determine arousals from sleep), chest wallmonitors (to document respiratory movements), nasal and oral air-flowmeasurements, and an electrocardiogram, among other parameters. Acombination of these and other factors are used by doctors and otherqualified sleep specialists to determine whether a patient has OSA.However, nocturnal polysomnography is generally expensive andtime-consuming. Furthermore, many patients experience the symptoms ofOSA (e.g., nocturnal arousals, snoring) while they are asleep, andtherefore, never recognize that they may have a sleeping disorder. As aresult, many patients with OSA may not seek proper diagnosis ortreatment of their sleeping disorder from a doctor or other qualifiedsleep specialist. Even if a patient is diagnosed with OSA, frequentlaboratory monitoring of the patient is generally not feasible due tothe expense and time involved in a nocturnal polysomnography.

The technology explosion in the implantable medical devices industry hasresulted in many new and innovative devices and methods for analyzingand improving the health of a patient. The class of implantable medicaldevices now includes pacemakers, implantable cardioverters,defibrillators, neural stimulators, and drug administering devices,among others. Today's state-of-the-art implantable medical devices arevastly more sophisticated and complex than early ones, capable ofperforming significantly more complex tasks. The therapeutic benefits ofsuch devices have been well proven.

There are many implementations of implantable medical devices thatprovide data acquisition of important physiological data from a humanbody. Many implantable medical devices are used for cardiac monitoringand therapy. Often these devices comprise sensors that are placed inblood vessels and/or chambers of the heart. Often these devices areoperatively coupled with implantable monitors and therapy deliverydevices. For example, such cardiac systems include implantable heartmonitors and therapy delivery devices, such as pacemakers,cardioverters, defibrillators, heart pumps, cardiomyostimulators,ischemia treatment devices, drug delivery devices, and other hearttherapy devices. Most of these cardiac systems include electrodes forsensing and gain amplifiers for recording and/or driving sense eventsignals from the inter-cardiac or remote electrogram (“EGM”).

Many patients who use implantable medical devices may be at risk forOSA. However, patients are generally left with traditional forms ofdiagnosis for OSA, such as nocturnal polysomnography. As mentioned,nocturnal polysomnography may be an expensive and time-consumingprocedure. Furthermore, many patients may not recognize that they havesymptoms relating to OSA, such that they would seek diagnosis andtreatment for the disorder. Nocturnal polysomnography is generally aninfrequent procedure that does not provide long term monitoring of thepatient's condition after he has been diagnosed. The present inventionis directed to overcoming, or at least reducing the effects of, one ormore of the problems set forth above.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an apparatus is provided fordetecting and monitoring obstructive sleep apnea. The apparatus includesan intracardiac impedance sensor to measure intracardiac impedance, amovement sensor to measure an amount of movement of a patient, and acontroller operatively coupled to said intracardiac impedance sensor andsaid movement sensor, said controller adapted to receive at least one ofan intracardiac impedance and the amount of movement of the patient anddetect obstructive sleep apnea based upon said intracardiac impedanceand said movement.

In another aspect of the present invention, a method is provided fordetecting and monitoring obstructive sleep apnea. The method includesmeasuring an intracardiac impedance to detect a change in theintracardiac impedance, measuring an amount of movement of a patient,and determining the presence of obstructive sleep apnea based upon thechange in the intracardiac impedance and the movement of the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numerals identify like elements, and in which:

FIG. 1 is a simplified diagram of an implementation of an implantablemedical device, in accordance with one illustrative embodiment of thepresent invention;

FIG. 2 illustrates a simplified block diagram representation of animplantable medical system in accordance with one illustrativeembodiment of the present invention;

FIG. 3 illustrates a more detailed block diagram representation of theimplantable medical device of FIGS. 1 and 2, in accordance with oneillustrative embodiment of the present invention; and

FIG. 4 illustrates a more detailed block diagram representation of aplurality of sensors and its associated data interfaces of FIG. 3, inaccordance with one illustrative embodiment of the present invention.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure.

There are many discrete processes involving the operation of implantablemedical devices (e.g., pacemakers, cardio defibrillators, and the like).The operation of an implantable medical device includes collecting,storing, and analyzing physiological data relating to a patient, and/ordelivering therapy (e.g., cardiac therapy) to a portion of a patient'sbody. Often, these tasks are performed by an implantable medical system,which includes an implantable medical device. Based upon the analysisperformed by the implantable medical system, one or more therapies maybe delivered to a particular portion of a patient's body. One example ofsuch a therapy is a cardiac therapy, which is delivered to a patient'sheart.

Embodiments of the present invention may be utilized to detect andmonitor the common symptoms and conditions related to patients withObstructive Sleep Apnea (OSA). It should be appreciated that the presentinvention may be included in an implantable device capable of collectingdata other than data used to diagnose or monitor OSA. The data may becollected by sensors in the implantable device and may be used bydoctors and other sleep experts to judge the severity of apneas and todetermine the efficacy of apnea therapy, without the use of nocturnalpolysomnography.

Turning now to FIG. 1, one embodiment of implementing an implantablemedical device into a human body is illustrated. A sensor device 210(e.g., devices attached to leads 114) placed upon the heart 116 of thehuman body 105 is used to acquire and process physiological data. In oneembodiment, the sensor device 210 may also be a therapy delivery device(described in greater detail below). An implantable medical device 220collects and processes a plurality of data acquired from the human body105. In one embodiment, the implantable medical device 220 may be acardiac pacemaker or an implantable cardiovertor defibrillator (“ICD”).The data acquired by the implantable medical device 220 can be monitoredby an external system, such as the access device 240 comprising aprogramming head 122, which remotely communicates with the implantablemedical device 220. The programming head 122 is utilized in accordancewith medical device programming systems known to those skilled in theart having the benefit of the present disclosure, for facilitatingtwo-way communication between the implantable medical device 220 and theaccess device 240.

In one embodiment, a plurality of access devices 240 can be employed tocollect a plurality of data, including OSA data, processed by theimplantable medical device 220 in accordance with embodiments of thepresent invention. The implantable medical device 220 is housed within ahermetically sealed, biologically inert outer canister or housing 113,which may itself be conductive so as to serve as an electrode in theimplantable medical device 220 pacing/sensing circuit. One or moresensors/leads, collectively identified with reference numeral 114 inFIG. 1, are electrically coupled to the implantable medical device 220and extended into the patient's heart 116 via a vein 118. Disposedgenerally near a distal end of the leads 114 are one or more exposedconductive electrodes (i.e., sensor device 210) for receiving electricalcardiac signals or delivering electrical pacing stimuli to the heart116. The leads 114 may be implanted with their distal end situated ineither the atrium or ventricle of the heart 116. In an alternativeembodiment, the sensor device 210, or the leads 114 associated with thesensor device 210, may be situated in a blood vessel on the heart 116,such as a vein 118.

Turning now to FIG. 2, a system 200, in accordance with one embodimentof the present invention, is illustrated. The system 200 comprises aplurality of sensor devices, collectively identified with referencenumeral 210 in FIG. 2, an implantable medical device 220, an accessdevice 240, and an interface 230 that provides a communication linkbetween the implantable medical device 220 and the access device 240.Embodiments of the present invention provide a plurality ofphysiological data from the sensor devices 210, which are then processedand stored in the implantable medical device 220. In one embodiment, thesensor devices 210 may collect data that is used to detect and monitorOSA in a patient.

As mentioned, based upon physiological data and other factors, theimplantable medical device 220 may deliver a therapy to a portion of thepatient's body, via the sensor devices 210. The access device 240 canthen be used to monitor and analyze the organized data from theimplantable medical device 220 via the interface 230 and view resultsfrom delivered therapy. The access device 240 can be used to monitor theefficiency of the therapy delivered by the implantable medical device220. The access device 240 can be used to determine, based upon datastored by the implantable medical device 220, whether a therapydelivered was of proper energy intensity.

Turning now to FIG. 3, a more detailed block diagram depiction of oneembodiment of the implantable medical device 220 is illustrated. Theimplantable medical device 220 comprises a processor 310, a controllogic 320, a memory unit 330, a data acquisition controller 340, atelemetry interface 350, and a plurality of data interfaces 360, 370,380, 390. The plurality of sensor devices 210 of FIG. 2 provides variousphysiological data to the implantable medical device 220. The processor310 controls the operation of the implantable medical device 220. Theprocessor 310 utilizes the control logic 320 to perform a plurality ofoperations, including memory access and storage operations. Theprocessor 310 communicates with the control logic 320 and the dataacquisition controller 340 via a bus line 325. The control logic 320sends control signals to the memory unit 330 for controlling andinstalling the memory unit 330, and to the data acquisition controller340, which controls the acquisition of physiological data and drivesoutput signals to the telemetry interface 350.

The telemetry interface 350 can facilitate real-time access ofphysiological data acquired by the data acquisition controller 340.Therefore, a physician can view physiological data on a real time basisby accessing the data acquisition controller 340, via the telemetryinterface 350. The data acquisition controller 340 can prompt the datainterfaces 360, 370, 380, 390 to retrieve physiological data from thesensor device 210, process such data, and deliver physiological data tothe data acquisition controller 340. The data interfaces 360, 370, 380,390 can perform a number of analog-to-digital conversions andtime-interval conversions, known to those skilled in the art, upon theacquired physiological data. The data interfaces 360, 370, 380, 390 canacquire, condition, and process physiological data and forward them tothe data acquisition controller 340.

It should be appreciated that, in an alternate embodiment, thefunctionality of the data interfaces 360, 370, 380, 390 may be combinedwith the sensor devices 210, such that information gathered by thesensor devices 210 may be readily utilized by the implantable medicaldevice 220 without further processing by another device or interface. Itshould also be appreciated that, although the sensor devices 210 areseparated from the implantable medical device 220 for illustrativepurposes in FIGS. 2 and 3, the implantable medical device 220 mayfurther comprise the sensor devices 210.

Turning now to FIG. 4, one embodiment of the sensor device 210 and theimplantable medical device 220 of FIGS. 1, 2 and 3, in accordance withthe present invention, is shown. In the illustrated embodiment of FIG.4, four sensors are shown. However, it should be appreciated that theimplantable medical device 220 may comprise of more or less sensors thanthe illustrated embodiment of FIG. 4, such that OSA may be properlydiagnosed on a patient. It should also be appreciated that thefunctionality of each sensor described below may be combined into one ormore sensors, such that OSA may be properly diagnosed on a patient.

The implantable medical device 220 comprises four sensors, whichindividually and in combination may be used to detect OSA in a patient.An intracardiac impedance sensor 210-1 measures impedance between anintracardiac atrial electrode and an intracardiac ventricular electrode.An intrathoracic impedance sensor 210-2 measures impedance across thethorax. In one embodiment, the intrathoracic impedance sensor 210-2 mayinclude pacemaker sensors, which measure impedance between a pacemakerand an intracardiac electrode. The impedance between the pacemaker andthe intracardiac electrode may be used to estimate in minute ventilation(“MV”). A movement sensor 210-3 detects movement in a patient duringsleep. The movement sensor 210-3, in one embodiment, may be a piezocrystal or an accelerometer. An electrical sensor 210-4 detects cardiacdepolarizations.

Using the four sensors 210-1, 210-2, 210-3, 210-4, a plurality ofinformation can be gathered to properly diagnosis OSA on a patient. Theinformation gathered by the sensors 210-1, 210-2, 210-3, and 210-4 isprocessed by an intracardiac data interface 360, an intrathoracicimpedance data interface 370, a movement data interface 380, and anelectrical data interface 390, respectively, before the information isforwarded to the data acquisition controller 340. Although sensors canbe used individually to diagnose OSA, combinations of two or moresensors may form a basis for diagnosis of OSA. For example, a largedecrease in impedance between atrial and ventricular electrodes (i.e., adecrease in the intracardiac impedance sensor 210-1) occurring when apatient is not exercising (i.e., a low reading from the movement sensor210-3) may be a factor towards diagnosis of OSA. As a patient attemptsto breathe while his airway is obstructed, negative intrathoracicpressure may increase, which overfills the right side of the heart. Thisoverfilling of the right side of the heart increases the diameter of theatrium and the ventricle. Although the volume of the heart does notchange, the shape of the heart becomes shorter and wider. As a result, adrop in atrial-to-ventricular impedance may be observed during OSAbecause the wider blood pool will cause a reduced impedance. The widerblood pool may also be a result vigorous exercise from the patient.Therefore, the intracardiac impedance sensor 210-1 may be read inconjunction with the movement sensor 210-3. In one embodiment, a lowreading from the movement sensor 210-3 indicates the patient is notexercising or in some other physical activity. A decrease in theintracardiac impedance sensor 210-1 and a low reading from the movementsensor 210-3 indicates a possibility that the patient has OSA.

Another possible indication that a patient has OSA may be provided bythe intrathoracic impedance sensor 210-2. In one embodiment, theintrathoracic impedance sensor 210-2 may measure impedance between animplantable device housing, such as a can electrode, and an endocardialelectrode, such as an atrial electrode or a ventricular electrode. Adecrease in intrathoracic impedance during attempted inspiration may bea factor in determining whether a patient has OSA. As a patient attemptsto breathe while his airway is obstructed, the circumference of histhorax may expand. As the patient's thorax expands, the diaphragm pushesthe heart and lungs upward. As the lungs are pushed upward, the lungs donot change volume, but instead become shorter and wider. The shorter andwider shape of the lungs may reduce intrathoracic impedance. Inaddition, as a patient attempts to breathe while his airway isobstructed, negative intrathoracic pressure may increase, whichoverfills the right side of the heart. As the right side of the heartoverflows, a wider blood pathway forms, thereby reducing intrathoracicimpedance. Furthermore, upward movement of the diaphragm pushes theheart closer to the implantable medical device 220, thereby reducingimpedance. A decrease in the intrathoracic impedance sensor 210-2indicates the possibility that the patient has OSA.

Another possible indication that a patient has OSA comes from a rapidincrease in impedance minute ventilation (“MV”) followed by a slowerdecrease in impedance MV. A person who does not have sleep apneabreathes normally during rest. A patient who has OSA usually cannotbreathe normally during rest because of an obstruction in the airway.While the patient's heart is attempting to pump blood into the lungs,the obstruction is preventing the patient from breathing. As a result,the patient's heart begins to pump faster to compensate for the lack ofblood flow. After an arousal event, the patient begins to breathe again,but because the heart was pumping fast before the arousal event, thepatient goes through a hyperpneic phase, which is a period of abnormallyrapid or deep breathing. Studies have shown that during the hyperpneicphase there may be an immediate rise in MV followed by a more gradualdrop in MV over a period of time.

An arousal event each time an obstruction is relieved may cause briefperiods of movement detectable by the movement sensor. As mentioned, inone embodiment, the movement sensor may be a piezo crystal or anaccelerometer. During the hyperpneic phase following the release of anobstruction, there is usually a brief arousal which can cause bodymovement detectable by movement sensors. A brief period of movementduring sleep coinciding with the dramatic increase in respiration (i.e.,a rapid increase in impedance MV followed by a slower decrease inimpedance MV), as described above, may indicate the patient has OSA. Animmediate rise in MV followed by a more gradual drop in MV, coupled witha brief of movement of sleep, indicates the possibility that the patienthas OSA.

Yet another possible indication that a patient has OSA may be providedby the electrical sensor 210-4. OSA can cause bradycardia during anobstruction. Bradycardia is an abnormally slow or unsteady heart rhythm(usually less than 60 beats per minute) that causes symptoms such asdizziness, fainting, fatigue, and shortness of breath. Release of theobstruction is generally accompanied by sinus tachycardia and possiblyincreased atrial-ventricular conduction. Sinus tachycardia is a fastheartbeat (usually more than 150 beats per minute) because of rapidfiring of the sinoatrial (i.e., sinus) node. Both sinus tachycardia andincreased atrial-ventricular conduction can be detected by intracardiacelectrodes and electrical sensing amplifiers or by subcutaneouselectrodes and electrical sensing amplifiers.

Referring back to FIG. 3, as the sensors 210-1, 210-2, 210-3, 210-4collect data, the data interfaces 360, 370, 380, 390 process the data,in accordance with conventional practice, and forwards the data to thedata acquisition controller 340. The processor 310 then utilizes thecontrol logic 320 to provide the data from the data acquisitioncontroller to the memory unit 330. In addition, a doctor or anotherqualified sleep professional may use the telemetry interface 350 tofacilitate real-time access to the data on the data acquisitioncontroller. The doctor or another qualified sleep specialist may analyzethe collected data to determine whether the patient has OSA.

The particular embodiments disclosed above are illustrative only, as theinvention may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. Furthermore, no limitations are intended to thedetails of construction or design herein shown, other than as describedin the claims below. It is therefore evident that the particularembodiments disclosed above may be altered or modified and all suchvariations are considered within the scope and spirit of the invention.Accordingly, the protection sought herein is as set forth in the claimsbelow.

1. A method of detecting and monitoring obstructive sleep apnea,comprising: measuring impedance minute ventilation to detect a change inthe impedance minute ventilation corresponding to a period of hyperpneicrespiration, wherein the change includes an increase in impedance minuteventilation followed by a decrease in impedance minute ventilation;detecting an increasing amount of movement of a patient during theperiod of hyperpneic respiration; and determining the presence ofobstructive sleep apnea responsive to the change in the impedance minuteventilation coinciding with the increasing movement of the patient.
 2. Amethod of claim 1, wherein measuring impedance minute ventilationfurther comprises detecting a rapid change in the increase in impedanceminute ventilation followed by a gradual change in the decrease inimpedance minute ventilation.
 3. A method of claim 1, wherein measuringthe increasing amount of movement of the patient further comprisesdetecting an amount of movement of the patient from a statecorresponding to a state of physical inactivity of the patient.
 4. Amedical device for detecting and monitoring obstructive sleep apnea,comprising: means for measuring impedance minute ventilation to detect achange in the impedance minute ventilation corresponding to a period ofhyperpneic respiration, wherein the change includes an increase inimpedance minute ventilation followed by a decrease in impedance minuteventilation; means for detecting an increasing amount of movement of apatient during the period of hyperpneic respiration; and means fordetermining the presence of obstructive sleep apnea responsive to thechange in the impedance minute ventilation coinciding with theincreasing movement of the patient.
 5. The method of claim 1, furthercomprising: correlating a decrease in intrathoracic impedance during anattempted inspiration of the patient with the presence of obstructivesleep apnea.
 6. The method of claim 1, wherein the impedance minuteventilation is measured between an electrode in an atrium of a heart andan electrode in a ventricle of a heart.
 7. The method of claim 1,wherein the impedance minute ventilation is measured between animplantable device housing and an endocardial electrode.
 8. The methodof claim 5, further comprising detecting an arousal of a patient fromsleep coinciding with the occurrence of the attempted inspiration. 9.The method of claim 8, further comprising determining an occurrence ofobstructive sleep apnea in response to detecting the occurrence of theattempted inspiration of the patient coinciding with detection ofarousal of the patient from sleep.